1. T. Ogawa 1, T. Adachi 2, and N. Nishitani 3 1) NICT, Japan 2) Stanford Univ., USA 3) STE Lab., Nagoya Univ., Japan Medium-Scale Traveling Ionospheric Disturbances Simultaneously Observed With the SuperDARN Hokkaido Radar and FORMOSAT/ISUAL SuperDARN Workshop 2011 Hanover, US 30 May – 3 June 2010

2. ・ SuperDARN Hokkaido HF Radar Imaging of horizontal two-dimensional MSTID structures over the Sea of Okhotsk from the north of Hokkaido to Kamchatka ・ FORMSAT-2 / ISUAL 630-nm Limb Imager Imaging of two-dimensional 630-nm airglow structures in the vertical along satellite path ・ Using the ISUAL imager and ground-based all-sky imager at Darwin, Adachi et al. (2011) first clarified three-dimensional 630-nm airglow structures. ・ In this presentation, we use the Hokkaido radar, ISUAL limb imager, and GPS-TEC data to investigate propagation and three-dimensional structure of MSTID. ISUAL (Imager for Sprites : Upper Atmospheric Lightning) FORMOSAT-2 ISUAL 630-nm Limb Imager

3. SuperDARN Hokkaido Radar GEONET Providing GPS-TEC Data Over Japan ~1,200 Rxs Rikubetsu (43.53 o N, 143.61 o E; geomag. 36.46 o N) ISUAL 630-nm Limb Imager (h ~ 900 km) MSTID

4. ～ 5000 km ～ 6000 km Long-Distance Propagation of Nighttime MSTID （ HF Radar + GPS + 630-nm Imager ） Long-Distance Propagation of Nighttime MSTID （ HF Radar + GPS + 630-nm Imager ） (Ogawa et al., 2009) Winter NightSummer Night

5. Range Res. = 45 km, Time Res. = 1 min 20 December 2006 1520 UT GPS-TEC Map at 1520 UT

6. 1520 UT 1456 UT Kp = 4-, 4- Dst = -26 (disturbed) HF FOV Satellite Track 1522:29 1456:49 Limb Obs. 20 Dec 2006 B0 B15 1522 UT Range Res. = 45 km Time Res. = 1 min 10.8 MHz

7. 1516 UT1519 UT1522 UT 20 December 2006 MSTID observed with radar and GEONET Velocity : ~90 m/s toward SW Period ： ~50 min Wavelengths ： ~270 - 500 km B8 Echo Power Doppler Velocity Beam 8 630-nm Deviation N-S wavelengths of ~100 - 500 km

8. Range Res. = 15 km, Time Res. = 1 min 29 December 2008 1325 UT GPS-TEC Map at 1325 UT

9. Kp = 0, 0+ (very quiet) 1325 UT Faint MSTID 1304 UT 1332 UT HF FOV 1332:35 1304:34 B0 B15 29 Dec 2008 Satellite Track Limb Obs. Range Res. = 15 km, Time Res. = 1 min 10.8 MHz

10. 1322 UT1325 UT1329 UT 29 December 2008 1332 UT MSTID structures are unclear compared with those on 20 and 21 December 2006 Wavelength : ~500 km B5 Echo Power Doppler Velocity Beam 5 N-S wavelength of ~ 500 km Small-scale structures with wavelengths of a few tens to 100 km Echoes return from strong horizontal gradients of Ne?

11. Winter Nighttime MSTID (Ogawa et al., 2009) Strong radar echoes tend to have negative Doppler velocities ?

12. MSTID SW E N Limb-view Obs. FORMOSAT-2 / ISUAL Limb-view Obs. The ISUAL imager cannot always clarify discrete MSTID structures when its field-of-view is not aligned with phase fronts of MSTID, in particular, in the case of 29 Dec. 2008 Latitude Altitude MSTID 630-nm (Ne) Vertical Structure Seen by ISUAL

13. ・ On 20 and 21 December 2006 (geomagnetically disturbed days), the Hokkaido HF radar detected southwestward-propagating MSTID with phase velocities of ~80-90 m/s, a period of ~50 min, and wavelengths of ~200-500 km. The ISUAL limb imager simultaneously observed airglow structures along N-S with horizontal wavelengths of ~100-500 km that were also seen in the radar data, though the imager FOVs were ~ 1000 km (or more) west of the radar FOV. ・ On 29 December 2008 (geomagnetically quiet day), the imager FOVs were within the radar FOV. Though MSTID signatures were rather faint, MSTID with a wavelength of ~500 km were observed with both the radar and imager. Both instruments also detected small- scale structures with wavelengths of a few tens to 100 km embedded within MSTID. Strong radar echoes tend to have negative Doppler velocities. ・ Thus, MSTID signatures observed with the radar seem to correspond to those detected with the ISUAL imager, though the imager cannot always clarify discrete MSTID structures when its FOV is not aligned with phase fronts of MSTID. ・ More simultaneous observations are required to investigate spatial relationship between radar (radio wave) and imager (optical) MSTID, and to know those between Ne irregularities and 630-nm airglow structures. Summary